EM cross-coupling (more informally, “cross-talk”) can occur between separate signal paths within circuitry integrated into or housed within microelectronic packages. EM cross-coupling may be particularly problematic in the context of small scale, high power RF applications. Consider, for example, an RF microelectronic package containing N-way Doherty PA circuitry and having a relatively compact form factor. By common design, such a microelectronic package may contain two or more high gain transistor die attached to a base flange in a side-by-side relationship. Bondwire arrays may electrically interconnect the transistor die with other circuit elements, such as the package terminals, integrated passive capacitors, or other devices contained within the package. Due to the close proximity of the transistor die and their corresponding bondwire arrays, EM cross-coupling can occur during package operation and, if sufficiently severe, may limit the performance of the RF PA circuitry; e.g., EM cross-coupling may displace impedances presented to the transistor die, which may detract from RF performance in terms of linearity, efficiency, peak power, or gain. Similarly, EM cross-coupling can likewise limit the performance of microelectronic devices containing other types of circuitry, which include signal paths extending in relatively close proximity and carrying distinct electrical signals.
There thus exists an ongoing demand for the provision of microelectronic packages having reduced susceptibility to EM cross-coupling, even when containing (e.g., RF) circuitry operated at higher power levels and possessing relatively compact form factors. Ideally, embodiments of such microelectronic assemblies would provide enhanced shielding of adjacent signal paths from EM cross-coupling, while maintaining high levels of package performance and remaining cost effective to manufacture. Similarly, it is desirable to provide methods for manufacturing microelectronic packages having such favorable characteristics. Other desirable features and characteristics of embodiments of the present disclosure will become apparent from the subsequent Detailed Description and the appended Claims, taken in conjunction with the accompanying drawings and the foregoing Background.
For simplicity and clarity of illustration, descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the exemplary and non-limiting embodiments of the invention described in the subsequent Detailed Description. It should further be understood that features or elements appearing in the accompanying figures are not necessarily drawn to scale unless otherwise stated. For example, the dimensions of certain elements or regions in the figures may be exaggerated relative to other elements or regions to improve understanding of embodiments of the invention.